The cost of diesel and gasoline kept on climbing over the past week, though not as fast as earlier in the month, largely because crude oil prices continue rising, according to the Energy Information Administration (EIA).

The U.S. average price for diesel is up roughly half a penny this week, climbing to $4.147/gal. compared to $4.142/gal. last week. Compared to the same time period last year, diesel is up nearly 22 cents per gallon, EIA noted.

California retains the most expensive per-gallon diesel price at $4.476, though that’s down half a penny from last week, followed by the West Coast region ($4.433), the Central Atlantic region ($4.279), and the New England area ($4.263). Diesel is cheapest in the Midwest ($4.046) followed by the Gulf Coast ($4.055) and the Rocky Mountain region ($4.136), the EIA said.

Gasoline prices, by contrast, are up more sharply according to the agency – climbing over 5 cents per gallon to a U.S. national average of $3.918 this week. That’s over 32 cents more per gallon compared to the same time period in 2011, EIA said.

California is again home to the highest price in the nation, as gasoline is $4.359/gal. there, though that’s down nearly 2 cents per gallon from last week. The regions with the most expensive gasoline prices per gallon are the West Coast ($4.242), the Midwest ($3.899) and the Central Atlantic area ($3.882). Gasoline is cheapest in the Rocky Mountain region ($3.687) and along the Gulf Coast ($3.758).

The EIA added that the national average price of regular grade gasoline averaged $3.58/gal. for the month of February, representing a 37 cent or 11.5% increase compared to February 2011; a historic high for the month of February in both real and nominal prices, the agency said.

That’s almost entirely due to global crude oil prices, which have also been at record levels for this time of year, EIA noted, with the Brent crude oil price averaging $119.33 per barrel in February, the highest of any February on record and an increase of $15.61 per barrel compared to a year earlier.

However, the agency stressed that cost-per-mile-driven is not at record highs because of improvements to overall vehicle fuel economy, pointing out that – adjusted for inflation – while cost-per-mile-driven averaged 23 cents in 1980, that number is estimated to now be between 16 cents and 17 cents per mile as of February this year.